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Posted to dev@tomcat.apache.org by "Konstantin Kolinko (Confluence)" <no...@apache.org> on 2019/11/23 23:20:08 UTC
[CONF] Apache Tomcat > Class Not Found Issues
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"Class Not Found Issues")
| | | | |  | | Konstantin
Kolinko edited this page
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| | Here's the version comment
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| | |  | | Konstantin
Kolinko edited at [11:18
PM](https://cwiki.apache.org/confluence/pages/viewpage.action?pageId=103098805)
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_Permalink_ to this page: [
https://cwiki.apache.org/confluence/x/tSklBg](https://cwiki.apache.org/confluence/x/tSklBg)
## Preface
This page discusses the various ways you see Class Not Found errors or very
similar errors. It is strongly advised you read the following topics:
* Classloader HOWTO pages: [Tomcat 9.0](https://tomcat.apache.org/tomcat-9.0-doc/class-loader-howto.html), [Tomcat 8.5](https://tomcat.apache.org/tomcat-8.5-doc/class-loader-howto.html), [Tomcat 7.0](https://tomcat.apache.org/tomcat-7.0-doc/class-loader-howto.html), (historic: [Tomcat 6.0](https://tomcat.apache.org/tomcat-6.0-doc/class-loader-howto.html)).
* [Don't](https://marc.info/?t=104317529200004&r=1&w=2) [use](https://marc.info/?t=104380440100003&r=1&w=2) [packageless](https://marc.info/?t=96947656900002&r=1&w=2) [classes](https://marc.info/?t=104491020100002&r=1&w=2) [and](https://marc.info/?t=104265576200003&r=1&w=2) [declare](https://marc.info/?t=104249748300001&r=1&w=2) [all](https://marc.info/?t=102996950100003&r=1&w=2) [imported classes](https://marc.info/?t=102922189400001&r=1&w=2)!
* [Another answer to a classloader issue](https://marc.info/?l=tomcat-user&m=103843452413727&w=2)
If you get a `NoClassDefFoundError` exception, the root cause might be the
same as for a `ClassNotFound` exception.
...
1. [Why is jsp:useBean is not working?](/confluence/pages/viewpage.action?pageId=103098805)
2. [Why do I get java.lang.NoClassDefFoundError: javax/servlet/Filter?](/confluence/pages/viewpage.action?pageId=103098805)
3. [Why do I get java.lang.NoClassDefFoundError: org/xml/sax/InputSource?](/confluence/pages/viewpage.action?pageId=103098805)
## Answers
### |
Anchor
---
| | Q1
---|---
| Q1
...
### Why is
...
### `jsp:useBean`
...
### is not working?
...
###
Make sure:
* Your bean is packaged in a class.
* You have fully qualified your class name (e.g.:
No Format
`com.bar.package.MyClass`
) OR
* You have imported your class into your jsp (e.g.:
No Format
`<%@ `
` page `
` import="com.bar.package.MyClass"%>`
)
###
Anchor
---
| | Q2
---|---
| Q2
...
### Why do I get
...
### `java.lang.NoClassDefFoundError: `
...
### ` javax/servlet/Filter`
...
### ?
...
###
You probably have servlet-api.jar floating around somewhere it shouldn't be.
This really messes up the classloaders since Tomcat's classloaders don't act
quite as normal as one expects (see links above). servlet-api.jar should only
be found only once in $CATALINA_HOME/lib.
###
Anchor
---
| | Q3
---|---
| Q3
...
### Why do I get
...
### `java.lang.NoClassDefFoundError: `
...
### ` org/xml/sax/InputSource`
...
### ?
...
###
You have conflicting XML api jar files in your classpath. Read the README or
RELEASE-NOTES for more information.
...
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